Proper motor oil question

[LakeRider]

My Mercruiser manual says I should use Quicksilver 4 cycle Marine engine oil (SAE 40W, SG or CD).I can't find this stuff anywhere.
It also says that in the event I can't find the 40w, I could use a 20W-40 (SG or CD). Would anyone know if there are more up-to date oils that could be used inplace of the above?

Thanks in advance.

 

[paulswagelock]

It is the API SG certification that you won't be able to find any longer. It has been superseded by SH, SJ, SL, SM, and now SN.

The key difference is the amount of Zinc and phosphourus in the oil, used for high pressure anti wear. Newer oils have less since it is bad for catalytic converters. Also, the straight weight 40 is old school thinking as well.

Luckily you have many choices that would be fine. Mercruiser 25w40 or 20w40 would work fine, as would Mobil 1 15w50. Also any of the dual rated HDEO like Rotella, Delvac, Delo, etc in the 15w40 weight would work fine. Those would be the best cost position for price versus performance. Use a good filter and change regularly, and any of these would be fine.

 

[garryowen]

It is the API SG certification that you won't be able to find any longer. It has been superseded by SH, SJ, SL, SM, and now SN.

The key difference is the amount of Zinc and phosphourus in the oil, used for high pressure anti wear. Newer oils have less since it is bad for catalytic converters. Also, the straight weight 40 is old school thinking as well.

Luckily you have many choices that would be fine. Mercruiser 25w40 or 20w40 would work fine, as would Mobil 1 15w50. Also any of the dual rated HDEO like Rotella, Delvac, Delo, etc in the 15w40 weight would work fine. Those would be the best cost position for price versus performance. Use a good filter and change regularly, and any of these would be fine.

very very good answer :smt038:grin:

 

[tbirdvet]

I have good luck using synthetic 25W40. if you need some here is a good deal:
http://www.ebay.com/itm/15081643552...LX:IT&_trksid=p3984.m1555.l2649#ht_500wt_1413

 

[LakeRider]

Thank you both!